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A method of two-dimensional measurement for evaluating finger motion impairment. A description of the method and comparison with angular measurement.

A new method has been designed for direct measurement of the two-dimensional range of motion (ROM) of the finger. The two-dimensional method encompasses the postures imposed by various combinations of contraction and relaxation of the finger motors, so that an individual muscle injury or adhesion might be more easily detected. The figures and values obtained from the two-dimensional method are easier to interpret than those from conventional measurements, making the progress of the rehabilitated finger more apparent. Since the passive ROM cannot be evaluated by this method, it is a supplement rather than a substitution for the conventional range of motion evaluation for each joint. The drawback of the two-dimensional method is that it is more difficult to use than the conventional method.

Adolescent↗

Analytical evaluation of the Dade Behring Dimension RxL automated N-Terminal proBNP (NT-proBNP) method and comparison with the Roche Elecsys 2010.

Methods to quantify B-type natriuretic peptide (BNP) and N-terminal-propeptide (NT-proBNP) in plasma or serum samples are well established. We assessed the analytical performance of the Dimension RxL NT-proBNP method (Dade-Behring). Evaluation of different sample types was carried out. Controls and heparin plasma pools were used to determine the detection limit, precision, and linearity. Sample stability and the effect of interfering substances on the NT-proBNP concentrations were evaluated. Agreement between Dimension RxL and Elecsys 2010 (Roche Diagnostics) NT-proBNP methods was assessed. The influence of age and sex on NT-proBNP concentrations was evaluated in healthy subjects. Heparin plasma should be the matrix of choice. The detection limit was 2.0 ng/L. The total imprecision was 2.6-3.6% for concentrations from 231 to 9471 ng/L; mean NT-proBNP concentrations of 21 and 15 ng/L were associated with coefficients of variation of 9.9% and 14.7%, respectively. The method was linear up to 32,650 ng/L. There was no effect of temperature, freeze-thaw cycles and interfering substances. A bias was detected when Dimension RxL and Elecsys 2010 NT-proBNP methods were compared. Age and sex were significantly and independently related to NT-proBNP concentrations. The Dimension RxL NT-proBNP method, like the Elecsys 2010, is suitable for routine use in the diagnosis of heart failure.

Adult↗

Biomechanical characteristics of the middle ear system measured by a new method. III: Comparisons with tympanometric measurements.

A new method for studying middle ear mechanics is reported in which we measured ear canal pressure changes due to tympanic membrane volume displacements. One feature of this pressure-volume relationship (PVR) is the determination of dynamic compliance of the middle ear system (MES). We found a significant correlation between dynamic compliance expressed by the PVR and static acoustic compliance by tympanometry. Another feature of the PVR was determination of the mechanical zero position of the tympanic membrane (TM) defined in terms of minimum hysteresis, which correlated significantly with the neutral position of the TM determined by tympanometry, but indicates a retracted position of the TM relative to tympanometry. Finally the hysteresis effect of the MES measured with the PVR was compared and found to fall within the range of peak difference found in bidirectional tympanometric recordings, which is also influenced by phase delay and semi-dynamic conditions.

Acoustic Impedance Tests↗

Comparison of methods for assessing in vitro antibiotic synergism against Pseudomonas and Serratia.

Infections with Pseudomonas aeruginosa and Serratia marcescens are often difficult to treat because of the narrow therapeutic ratio of available antimicrobials. Synergistic inhibitory and bactericidal activity for gentamicin and carbenicillin against P. aeruginosa has been documented in vitro. The purpose of this study was to compare 4 methods of determining in vitro synergism between several aminoglycosides and penicillins. The agar dilution method using an inoculum replicator was employed, and a drug combination showing inhibition equal to or less than one-fourth of the individual minimal inhibitory concentrations was termed synergistic. Combinations using amikacin and BL-P1654 showed synergism against a greater per cent of strains of P. aeruginosa and S. marcescens than combinations using gentamicin or carbenicillin. Additionally, the "checkerboard" broth dilution method using both minimal inhibitory concentration and minimal bactericidal concentration as endpoints and killing curves according to the methods of Jawetz was studied. Comparison of the results of these 4 methods showed excellent correlation, verifying the consistency of the 4 techniques for determining in vitro synergism.

Amikacin↗

Comparison of methods for determination of volatile organic compounds in drinking water.

Comparison of four methods including liquid-liquid extraction (LLE), direct aqueous injection (DAI), purge and trap (PAT) and head space (HS) were carried out in this work for determination of volatile organic compounds (VOCs) including trihalomethanes (THMs) in drinking water. This comparison is made especially to show the advantages and disadvantages and specifically the different detection limits (DL) that can be obtained for a given type of analysis. LLE is applicable only for determination of the THMs concentrations, while DAI, PAT, HS methods with different DL each of them are applicable for all VOCs, with PAT to be the most sensitive. Sampling apparatus and procedure for all these methods except of PAT are very simple and easy, but possible disadvantages for LLE and DAI are the low sensitivity and especially the detection only of THMs with LLE.

Chemistry Techniques, Analytical↗

[Fair hospital comparisons -- does the method contracted in Germany enable unbiased results?].

AIM: To evaluate the method for comparison of average length of stay in hospitals as defined in a contract between German health insurance companies and the "Deutsche Krankenhausgesellschaft" (German Hospital Association). METHOD: Simulation study executing the algorithm agreed upon in different scenarios, which varied the number of hospitals to be compared, the dispersion of diagnostic specialization over hospitals, and the distribution of hospitals' sizes. Scenarios were constructed to realistically reflect the situation in German inpatient treatment of mentally ill patients. RESULTS: By fixing casemix adjustments only on diagnoses of patients and by doing so aggregated on the level of hospitals, the method for comparison yielded artificial differences between hospitals even in a situation where each patient is treated with exactly the same amount of resource allocation (given the individual needs defined for all scenarios). Results of artificial differences were heavily biased against or in favour of the reference hospitals according to the specific condition of the scenario parameters. CONCLUSION: The contracted method is not capable of achieving fair hospital comparisons, at least not for psychiatric hospitals.

Algorithms↗

Two direct radioimmunoassays for 17 beta-estradiol evaluated for use in monitoring in vitro fertilization.

Two direct 125I radioimmunoassays for 17 beta-estradiol were evaluated by comparing results with those obtained by a comparison RIA involving extraction and chromatography (x) and with ultrasound parameters of ovarian activity. The correlation coefficients (R2) for the Immuchem Covalent-Coat Solid Phase 125I results (y1) and the Pantex Immuno-direct results (y2) with the comparison method results were 0.56 and 0.96, respectively, after log transformation of data (N = 42). Similar differences were observed in the correlations with the ultrasound parameters. We also evaluated the untransformed data by linear regression and obtained: y1 = 254 + 0. 410x (R2 = 0.65) and y2 = 48.2 + 0. 749x (R2 = 0.96). Between- and within-assay variations for a serum pool containing 17 beta-estradiol at 1278 pg/mL were respectively 9.0% and 9.4% for Immuchem , 3.3% and 6.7% for Pantex , and 7.3% and 9.4% for the comparison method; for the 267 pg/mL pool, these were 21.8% and 16.6% for Immuchem , 4.7% and 4.6% for Pantex , and 21.2% and 13.1% for the comparison method. Differences in the results obtained with the Pantex method and the comparison method were not clinically significant for monitoring superovulation for in vitro fertilization; the performance of the Immuchem method was less satisfactory.

Estradiol↗

Innotrac Aio!: a point-of-care or a routine analyzer? Analytical performance and plasma/whole blood comparison.

BACKGROUND AND METHODS: The aim of the present study was to evaluate the analytical performance of the Innotrac Aio! analyzer in measuring the cardiac markers troponin I (TnI), myoglobin (Myo) and creatine kinase-MB (CK-MB), both in lithium heparin plasma and in whole blood. RESULTS: TnI analytical sensitivity was 0.012 microg/L and the concentration corresponding to CV=10% was 0.036 microg/L. In healthy subjects, the 99th percentile TnI values were 0.023 and 0.016 microg/L in whole blood and in plasma, respectively. One hundred samples were tested both in whole blood and in plasma: TnI-whole-blood=1.16-plasma+0.011, bias=+0.18 (95% CI from -0.22 to +0.59); Myo-whole-blood=1.04-plasma-1.93, bias=+1.08 (95% CI from -6.17 to +8.32); CK-MB-whole-blood=1.11-plasma-0.09, bias=+0.96 (95% CI from -0.53 to +2.45). The method comparison with the RxL Dimension analyzer for TnI and Myo gave the following results: TnI Aio!=0.30 TnI RxL+0.00; bias=-5.80 (95% CI from -7.81 to -3.78), Myo Aio!=1.33 Myo RxL+0.42, bias=+53.09 (95% CI from +38.44 to +67.74). CONCLUSIONS: The analytical performance of the Innotrac Aio! analyzer was satisfactory for all three cardiac markers evaluated and, in particular, the TnI method provided sensitive and accurate results. The most important finding in this study is the possibility to perform the tests as either routine or point-of-care analysis, thus overcoming the variability of results obtained employing different methods.

Biomarkers↗

Automated computation of the Gyrification Index in prefrontal lobes: methods and comparison with manual implementation.

In this paper, we introduce an automated method of calculating Gyrification Index (GI), a measure of cortical folding. Automated GI (A-GI) is an in vivo GI implementation applied to MRI T1 weighted scans and is designed as an extension to the SPM analysis package. The A-GI tool is unbiased in its application, and is unlimited in the size of test cohort to which it can be applied. In comparison to manual methods, A-GI substantially reduces the time costs and improves repeatability. The current A-GI implementation is limited to analysis of prefrontal lobes, but an extension to provide whole brain A-GI is under consideration. In determination of the GI inner contour, A-GI traces high spatial frequencies typically missed in manual tracing, and thus, A-GI reports a high GI value. We examine the operation of this tool in two scan cohorts. We establish that the tool has good repeatability through its application to a cohort where 5 well individuals were scanned 5 times over a period of 6 months. This indicates that A-GI has low susceptibility to scanner noise and is not affected by the variability in brain representation given by repeat scans. We demonstrate replication of hand tracing results by comparisons with a manual GI study that has shown differences between high risk subjects who go on to develop schizophrenia and those who are at high risk but remain well. Direct scan by scan comparisons are carried out between manual and A-GI methods. In respect of scan orientation and coronal sampling, the methods differ, and these considerations contribute to a between methods right prefrontal ICC of 0.67 and left prefrontal ICC of 0.63. The replication results demonstrate that A-GI has discriminatory power equivalent to manual methods. A-GI is therefore a reliable measure of cortical folding that could be usefully applied to a number of MRI data sets of the brain in health and disease.

Frontal Lobe↗

Comparison of methods for the prediction of phenytoin concentrations.

A comparison was made of different methods for the prediction of the serum concentrations of phenytoin (PHT) at steady-state with a view to determining which of them had the best predictive performance. The methods employed calculated the predicted concentrations based on a dose steady-state concentration pair. Two of the methods used involved solving the Michaelis-Menten equation, determination of a single parameter in each individual and maintaining the Km (Method A) or Vmax (Method B) values at a constant. Methods C and D were Bayesian techniques that used population parameters determined in a population studied by us (Method C) and parameters drawn from the literature (Method D). Calculation of bias and precision suggests that Method C is the most suitable of those studied, with a mean prediction error (ME) of 0.56 +/- 2.16 mg/litre, a mean absolute error (MAE) of 1.76 +/- 1.31 mg/litre and a root mean squared prediction error (RMSE) of 2.17 mg/litre. Method C was also the method that showed the lowest percentage of underestimation (5.26%) and overestimation (10.53%).

Adolescent↗

Characterization of methanol-water and acetonitrile-water association using multivariate curve resolution methods

The solvatochromic comparison method has been used to probe the interactions of solutes with binary solvent mixtures of methanol-water and acetonitrile-water. The solute spectra recorded in these mixtures are composed of the additive spectral contributions of the different solvated species of the solute, i.e., the water-solvated species, the cosolvent-solvated species, and the species solvated by water-solvent complexes. Multivariate curve resolution-alternating least squares has been used to model the solvation of the solutes as a function of the composition of the binary solvent mixture. Spectra and concentration profiles of the dye surrounded by the different solvation environments have been isolated. For the first time, solute spectra solvated exclusively by methanol-water and acetonitrile-water complexes have been obtained, and the solvatochromic parameters of dipolarity/polarizability and hydrogen-bonding acidity have been estimated for these complex species.

Journal Article↗

Glycated haemoglobin: comparison between methods based upon 5-hydroxymethylfurfural determination (colorimetric or HPLC) and ion exchange chromatography (HbA1).

A comparison of methods, two based upon 5-hydroxymethylfurfural determination (colorimetric using a semi-automated procedure and HPLC) and ion exchange chromatography (HbA1 using BioRad method) was performed. The influence of variables on 5-hydroxymethylfurfural determination is reported. The dialysis step appears to be essential for an accurate determination of 5-hydroxymethylfurfural released from glycated haemoglobin. The adjustment of haemoglobin concentration to an accurately known level is required for the colorimetric method, in order to achieve the same background colour absorbance. For the HPLC method this step is not necessary as 5-hydroxymethylfurfural liberation was proved to be stoichiometric. The Sep Pak C-18 cartridge purification appears to be an improvement for the accurate determination of 5-hydroxymethylfurfural using HPLC. When the three methods were compared the overlap between normals and diabetics was found to be less, using the 5-hydroxymethylfurfural HPLC method, suggesting that this procedure, although more time consuming, seems to be more useful in the management of diabetes mellitus.

Chromatography, High Pressure Liquid↗

Comparison of two homogeneous HDL cholesterol methods in a large population study.

OBJECTIVES: High-density lipoprotein cholesterol (HDL-C) is an independent risk factor for coronary heart disease. Data are lacking on the performance of homogeneous methods using a large number of samples. DESIGN AND METHODS: We compared the performance of two HDL-C direct assays, the Dimension RxL (the Dade method) and the COBAS INTEGRA (the Roche method), for population screening. Performance was assessed using 4214 sera obtained from the International Collaborative Study on Atherosclerosis and Stroke In Asia (InterASIA) participants. RESULTS: The method comparison results demonstrated that both methods were highly correlated (r = 0.972). Deming regression analysis showed a slope of 1.009 +/- 0.007, an intercept of 0.048 +/- 0.009 and a S(y/x) of 0.08. The means were 1.29 +/- 0.33 and 1.23 +/- 0.33 mmol/l for the Roche and Dade methods, respectively, and the range of observed values were 0.30-3.05 and 0.19-2.86 mmol/l, respectively. The 95% confidence interval for the mean of the method differences was -0.10 to 0.22 mmol/l. Percentages of low (> or = 1.55 mmol/l), normal (1.03-1.54 mmol/l), and high risk (< 1.03 mmol/l) results were 15.5, 55.4, 29.0 for the Dade and 19.3, 59.3, 21.4 for the Roche method. The percentage of concordantly classified subjects at each cut point was 77.1%, 84.4%, and 95.5%. The percentage of overall consistency subjects was 85.4%. Thirteen percent of subjects were discordantly classified into the higher-risk group while the 1.6% of subjects were discordantly classified into the lower-risk group. CONCLUSIONS: Both homogeneous HDL-C methods were correlated and agree well with one another. The percentage of concordantly classified subjects was high. Thus, either method is suitable for large population studies.

Blood Chemical Analysis↗

Comparison of five automated serum and whole blood folate assays.

Serum and whole blood folate measurements are used to establish folate deficiency. Most methods used in clinical laboratories are automated, nonistopic methods that use folate-binding protein. Linearity, imprecision, and method comparison studies, including serum and whole blood hemolysates, were performed with the Access, Advia Centaur, ARCHITECT i2000, Elecsys 2010, and IMMULITE 2000 methods. The QuantaPhase II radioassay served as the comparison method. (Proprietary information is given in the text.) The Access and IMMULITE 2000 methods had higher systematic errors in linearity studies than the other 3 methods. The imprecision of all methods was acceptable (coefficient of variation, < 10%) even at low folate concentrations with the exception of the Elecsys 2010 (coefficient of variation, 16%). Method comparison studies using serum samples revealed calibration differences between the Access and Elecsys 2010 methods and the comparison method. Method comparison studies using whole blood samples showed poorer agreement between each of the automated methods and the comparison method than was seen with serum samples. The ARCHITECT i2000 folate assay demonstrated the best analytic performance. The poor agreement seen with whole blood hemolysates likely is due to calibration differences and differences in hemolysate preparation conditions.

Blood Chemical Analysis↗

[Two-stage reimplantation using spacers--the method of choice in treatment of hip joint prosthesis-related infections. Comparison with methods used from 1979 to 1998].

PURPOSE OF THE STUDY: Several therapies are available for the treatment of deep infection in total hip arthroplasty but none is completely successful; there is no consensus on an optimal method. The aim of this study was to evaluate the treatment used in our institution and its outcomes over the last 20 years. In each method, the success of treatment was evaluated in terms of both infection control and restoration of function in the treated joint. MATERIAL: A total of 172 patients with infected total hip replacements were treated at the First Orthopedic Clinic of the First Faculty of Medicine, Charles University, Prague, between 1979 and 1998. Our sample consisted of 132 patients, 92 men and 40 women. Resection arthroplasty was performed in 62 patients. Two-stage reimplantation was used in 64 patients. Two-stage reimplantation involving skeletal traction was applied in 35 and a block spacer was used in 29 patients. The remaining patients were treated by other techniques. METHODS: The type of infection was classified according to the Coventry system. The outcome of surgery was assessed on the basis of the Tsukayma rating system, radiographic findings and the Harris hip score. RESULTS: The average follow-up time from the definitive operation was 70.8 months. In the patients who had resection arthroplasty only, the cure rate of infection was 91.9%. However, an increase in the Harris hip score, as compared with the condition before surgery, was low (9.7 points). In the patients treated by the two-stage reimplantation without a spacer but with skeletal traction, the cure rate of infection was 94.3% and the Harris score increased by 20 points. The patients who were treated by two-stage reimplantation with a spacer showed an infection cure rate of 96.5% and an increase in the Harris score by 29 points. This increase was higher by 9 points in comparison with the patients who had reimplantation without the use of a spacer. An even greater difference (28.2 points) was found when the outcomes of this technique were compared with those of resection arthroplasty. The incidence of spacer dislocation in 21% of the cases was an unexpected finding. DISCUSSION: No great differences in outcome in terms of infection cure rate were found among the methods used, i.e., two-stage reimplantation facilitated a better function for the hip joint than Girdlestone's operation. The use of a spacer in two-stage reimplantation ensured a greater comfort for the patient during treatment and gave better results in terms of joint function than treatment without a spacer. The use of a cemented spacer is an optimal method that not only ensures the stability of a limb during the period necessary for infection control but also provides conditions for the prospective implantation of a new prosthesis. The spacer also permits delivery of high-dose local antibiotics released from the cement as well as makes space for a long-term application of antibiotic-containing lavage. CONCLUSIONS: The rate of success in the treatment of an infected hip arthroplasty and the possibility of preserving the implant and thus enabling the patient to move comfortably are currently high. The prerequisite is early diagnosis and a radical surgical approach that involves the use of a method leading to the most effective eradication of infection and the maintenance of a good function for the joint. The reimplantation of a new prosthesis, after removal of the previous one and debridement of all infected tissue and material, combined with a targeted antibiotic therapy, is the method of choice for both the patient and the surgeon.

Adult↗

Imaging phase objects with square-root, Foucault, and Hoffman real filters: a comparison.

Methods of imaging phase objects are considered. First the square-root filter is inferred from a definition of fractional-order derivatives given in terms of the integration of a fractional order called the Riemann-Liouville integral. Then we present a comparison of the performance of three frequency-domain real filters: square root, Foucault, and Hoffman. The phase-object imaging method is useful as a phase-shift measurement technique under the condition that the output image intensity is a known function of object phase. For the square-root filter it is the first derivative of the object phase function. The Foucault filter, in spite of its position, gives output image intensities expressed by Hilbert transforms. The output image intensity obtained with the Hoffman filter is not expressed by an analytical formula. The performance of the filters in a 4f imaging system with coherent illumination is simulated by use of VirtualLab 1.0 software.

Journal Article↗

Interlaboratory comparison of methods To quantify microsclerotia of verticillium dahliae in soil

In a comparison of different methods for estimating Verticillium dahliae in soil, 14 soil samples were analyzed in a blinded fashion by 13 research groups in seven countries, using their preferred methods. One group analyzed only four samples. Twelve soil samples were naturally infested, and two had known numbers of microsclerotia of V. dahliae added to them. In addition, a control was included to determine whether transport had an effect on the results. Results differed considerably among the research groups. There was a 118-fold difference between the groups with the lowest and highest mean estimates. Results of the other groups were evenly distributed between these extremes. In general, methods based on plating dry soil samples gave higher numbers of V. dahliae than did plating of an aqueous soil suspension. Recovery of V. dahliae from samples with added microsclerotia varied from 0 to 59%. Most of the variability within each analysis was at the petri dish level. The results indicate the necessity to check the performance of detection assays regularly by comparing recoveries with other laboratories, using a common set of soil samples. We conclude that wet plating assays are less accurate than dry plating assays.

Journal Article↗

Amylase in urine as measured by a single-step chromolytic method.

We studied a new single-step direct chromolytic method (Behring D.A.T.) for measuring urinary amylase (1,4-alpha-D-glucan glucanohydrolase, EC 3.2.1.1) activity, comparing results with those by a similar, but two-step, procedure that requires an auxiliary (coupling) enzyme. The two methods gave virtually identical relative responses to purified human pancreatic and salivary amylases. Assay of four quality-control materials to evaluate the total (day-to-day) precision of the new method yielded CVs of 4 to 7%, similar to those of the comparison method for each of the four quality-control samples. Amylase activity was measured by both methods in 110 random (i.e., untimed) urine specimens. Linear regression analysis provided a slope and y-intercept of 0.947 and 4 U/L (x = comparison method, y = direct method), respectively, and a standard error of the estimate of 25 U/L for specimens in which the amylase activities ranged from 11 to 1465 U/L (mean = 358 U/L) by the comparison method. The mean rate of amylase excretion in 2-h timed urine specimens from 95 healthy volunteers, as measured by the new method, was 7.18 (SD = 3.18) U/h, and the nonparametric (95% confidence interval) reference interval was 1.6 to 15.2 U/h. We consider the new method a promising alternative to other kinetic assays that require the use of auxiliary enzymes.

Amylases↗